How to secure Suse rescue distro ?

Hi, I intend to use Asterisk pbx with minimal Suse install. I'd also like to create installation CDROM and later also live CD. I've heard from quite some people that they use Asterisk with ssh+Suse rescue system as minimal Suse installation. I wonder how secure can that be out of the box, and what steps should I do to secure it ? Are there any scripts that would help me to do it ? Thanks in advance and sorry for newbie questions, Regards, Robert.